Not Applicable.
Not Applicable.
Wireless communication systems for interconnection with telephone systems are known. Such systems include a fixed transceiver which is connected to a telephone line and functions to relay signals to and from a remote device. Wireless systems allow substantial freedom of movement during a telephone conversation since the user is not limited by a fixed connection such as a telephone cord. However, some wireless systems provide relatively poor audio reproduction quality. More particularly, background noise and electromagnetic interference are significant sources of poor audio quality. Further, since the remote devices in such wireless systems are typically battery powered, power consumption is an important concern. It is therefore desirable to have a wireless communication system which provides energy efficient operation, high quality audio, security, and which reduces interference between closely spaced units.
In accordance with the present invention, a wireless communication system for use in connection with a telephone system includes a first transceiver with a first transmit circuit and a first receive circuit, said first transceiver being connected to the telephone system; and a second transceiver with a second transmit circuit and a second receive circuit, wherein the first and second transmit circuits transmit signals and the first and second receive circuits receive the signals from the second and first transmit circuits, respectively. In further accordance with the present invention, distinct signal transmission bands and carrier signal wavelengths may be employed to further improve audio quality.
Improved audio quality is provided by the communication system of the present invention with several advantageous features. Improved audio quality is provided by using FM sinusoidal current signal transmission between the base station and the remote wireless set. The FM sinusoid current signal transmission is advantageously resistant to the electromagnetic interference which negatively effects some known systems. Improved audio quality is also provided by transmitting at frequencies which avoid excessive harmonic overlap. For example, the first transceiver, which may be a base station, may transmit at 250-430 KHz while the second transceiver, which may be a remote wireless set, may transmit at 1.45-1.63 MHz. Improved audio quality is also provided by sending transmissions from the first transceiver with a carrier signal having a different wavelength than that with which transmissions are sent from the second transceiver, thus reducing cross-talk and reflection problems. LEDs which emit signals at a wavelength of 940 nm may be employed by the base station while the remote wireless set may employ LEDs which emit signals at a wavelength of 880 nm.
In addition to the above advantages, infrared communication offers inherent advantages insofar as IR signals are generally confined to the room in which they are transmitted. As such, IR systems provide a measure of privacy which is not ordinarily available in wireless communication systems. Further, systems can be used in close proximity without interference, for example in adjacent rooms. The present invention also reduces receiver desensitization problems.